Just wondering if someone would be kind enough to offer me some advice.

Ive been reading a few posts here with regards to perspective...however, I am a bit confused as to what to do with regards to some technical aspects of my next project.

------------------------------------------

- I intend to create a mattepainting using mainly combined photographs (which I will take myself) and some creative manipulation and combination in photoshop...

The main intention for this is to create a stylised but photo-realistic landscape environment in which I can composite someone shot against a bluescreen.
The mattepainting(s) will also be used to create a simple 2.5D mattepainting so I can also introduce some movement as well.

So theoretically, it is compositing live action in a combined live action/cg environment - if you are still following me

My question is how do I go about perspective.

Should I take all the photos at the same focal length? (in this case they are mainly going to be mountains, rocks etc)lets say for example 50mm
If they are then combined to make a mattepainting, would this still be the same focal length - 50mm - even if it is extended a bit or objects are placed in all different places?

And what about shooting the live action - the studio is quite small, so if I wanted someone to look like they are in the distance, I couldnt use a really long lens, I would have to shrink them in post - so using the example, would I have to maintiain shooting at 50mm?

I understand that it is not the lens that is distorting the image, it is the distance they are from the lens - so this is what i am concerned about.

Also - in the 3D CG environment, if I project the painting onto geometry, would my projection camera also have to be set up to be the example 50mm? Because..if I have extended the picture so it is really wide for panning purposes...wouldnt this mean I have a different field of view?

Wow, ive confused myself further in writing this...I hope someone is able to help me...if they have been brave enough to get this far in the post.

Hi
i suggest you do a 3d mokup of your shot if you are not confortable with perspective. It will be a good idea to establish the pov your pseudo-lens and the light.
Than you will know what kind of distortion the object will have regading their distance to the camera.
It will help you a lot for your shooting.

You should consider your photo footage as raw material that you are going to cut extract sample and more.
So basicaly any footage with any kind of lens might work (except maybe high distorted small lenses, or "big" lenses that give you a very flat depth of field aspect)
You can even use those big or small lens for special purposes like very far background or objects close to the camera.
Matte painting is not a science, and most of it is experiment.

For the live action, it will realy depend what kind of movement your comedian is going to do.
If he is going to do In-of-screen or a out-of-screen be carefull with lens
especialy if he is coming/going from one side of the frame.
choose like a 50mm if you want to reduce the footage and you dont want too much distortion on your live action.

For camera proj
If you are doing a building for example.
you want to map ,as cam proj some footage that you have done, on a 3d geometry.

When you are shooting your footage be sure to write down the camera lens you are using, the distance you are from the object you want to rebuild and aproximative tilt and pan.
If its an entire scene, do a map with correct distance height/width/depth of each object (yes this is painfull).
But you can have some helps by softwares like "photo modler". It works
with 4 shots (with minor perspectives changes) . you give some points (like the antena on the top of the building, or the neon sign) and after 20 or 60 corelation points it give you a camera.

But you can also make some cam proj from scrath with a totaly fake camera lens and it will works
once again its a lot of experimentation.